In medieval angelology there were traditionally nine orders to the celestial hierarchy; cats proverbially have nine lives; nine days or nights is the period during which a novelty is supposed to attract attention.
Nine Days' Queen a name for Lady Jane Grey (1537–54), Queen of England for nine days following the death of Edward VI. She was quickly deposed by forces loyal to Edward's (Catholic) sister Mary, who had popular support, and executed the following year.
nine days' wonder a person who or thing which is briefly famous.
nine-eleven (written 9/11, in American usage) refers to the terrorist action of 11 September 2001, in which hijacked passenger planes were flown into the World Trade Center and the Pentagon, and a fourth hijacked plane crashed near Pittsburgh.
nine men's morris a game, also known as merrill, played on a board between two players, each with an equal number of pebbles, discs of wood or metal, pegs, or pins.
nine tailors make a man proverbial saying, early 17th century; the literal meaning is that a gentleman must select his attire from various sources. It is now also associated with bell-ringing: tailors = tellers = strokes, the number of strokes on the passing bell indicating the sex of the deceased.
nine times out of ten on nearly every occasion.
nine-to-five used in reference to typical office hours, often to express an idea of predictable routine.
Nine Worthies nine famous personages of ancient Jewish and classical and medieval Christian history and legend (Joshua, David, and Judas Maccabaeus; Hector, Alexander, and Julius Caesar; and King Arthur, Charlemagne, and Godfrey of Bouillon).
to the nines to a great or elaborate extent (now often in dressed up to the nines). The origin is unclear: it could refer to the number just below the highest point in a scale of 1 to 10, or to the nine Muses. It has also been suggested that it could represent a misdivision of an unrecorded medieval phrase ‘to the eyne [eyes]’. The later association with dress may have been influenced by the 19th-century sartorial reputation of the 99th Wiltshire Regiment.
See also cat o' nine tails, on cloud nine, the whole nine yards.